Effects of Premature Loss of Deciduous Molars

The premature loss of primary molars results in the loss of space in either arch with varying degrees of impact, depending upon which tooth was lost early, in which arch, and the age at the time of the exfoliation. In the Montreal sample, far greater carious destruction was recorded in the lower arch. The rate of space loss varied accordingly, as did the impact on occlusion and response at reemergence of the succedaneous replacement tooth. The thesis was a collaborative work, bringing together the terrific growth sample collected by Dr. Arto Demirjian at the Universite de Montreal, the three-dimensional measuring device — the Optocom — of Dr. Frans vander Linden of the Netherlands, and the resources of the Center of Human Growth and Development, as provided by Dr. Robert Moyers and ably delivered by Bob Wainwright, both of Ann Arbor.

Abstract:Much has been written regarding the effects of premature loss of deciduous teeth on the dentition. Unfortunately, most reports are based on cross-sectional data, limited sample size and crude methodologies that have sometimes led to misconceptions. Computer-interfaced three-dimensional recording equipment now enables much more precise quantification and evaluation.

This study uses longitudinal data to compare mean spatial changes in the dental arch subsequent to premature loss of deciduous molars with the changes that occur in undisturbed arches.

Numerous aspects must be considered in studying this problem, so the report is divided to examine various questions independently. These include the dimension of space loss (Part I), the direction from which it is lost (Part II), the influence of age (at exfoliation) on the rate of space loss (Part III), the regaining of space at the time of emergence of the succedaneous teeth (Part IV), the effect on Angle classifications as measured at the molar and canine (Part V), and finally, schematic models to describe the combination of changes that take place (Part VI).

Each section includes a literature review, findings and discussion relevant to that subject.

Summarized findings:

The premature loss of any primary molar results in a mean loss of space, as measured by D-E Space. (the space occupied by the first and second primary molars).

In both arches, the greatest amount of space loss occurs as a result of the molar moving toward the mesial. The only case where the ultimate space loss attributable to the molar is not significantly greater than in the controls is in the maxillary D-Loss group. Here, as is the case in the mandibular D-Loss group, the cuspid is farther mesial than in the controls at the end of the series.

The age at which a tooth is lost is very significant in determining the amount of space during the first year. Younger individuals lose significantly more space in the first year following an extraction than do older individuals. Further, the mean space loss in the first year for all groups was significantly greater than that loss in any subsequent year. The phenomenon of greater loss due to the earlier loss of the primary tooth was far more profound in the maxilla than in the mandible.

There was no meaningful amount of space regained at the time of replacement by the succedaneous tooth.

Generally, premature loss affects molar and cuspid Angle classifications as might be expected, but the amount of destruction (premature loss in opposing arches) confounded demonstration of this phenomenon in our reconstructions.

Schematic representations of the mean changes in D-E Space, which are constructed by charting all groups according to their divergence from the controls. The control D-E Space is represented as a fixed length, with one-year annual incremental values plotted in a cumulative fashion assuming that all groups are identical at the beginning of the survey (normalizing the data). These figures clearly demonstrate the mean changes in space, and where they occur.

Much of this is complicated material, and justice is not served by summary alone. It is highly recommended that the article be studied in its entirety for comprehensive, contextual understanding.